        #include <stdio.h>
int search(int arr[],int n,int b){
    int low=0;
    int high=n-1;
    
    while(low<=high){int mid=low+(high-low)/2;
        if(b>arr[mid]){
            low=mid+1;
        }else if(arr[mid]>b){
            high=mid-1;
        }else{
            return mid;
        }
        
    }
    printf("error");
    return -1;
}
int main(){
    int arr[1000];
    int n=sizeof(arr)/sizeof(arr[0]);
    for(int i=0;i<1000;i++){
        arr[i]=i;
    }
    int b=519;
    int index=search(arr,n,b);
    if(index!=-1){
        printf("find");
    }
}